1 Science of Nutrition Exam 2 Chapters 3 7 4 5 By Alyssa Kosh 2 Chapter 3 The Human Body Are We What We Really Eat A Why do we want to eat what we want to eat Hunger a physiologic sensation that prompts us to eat the drive is nonspecific a variety of foods could satisfy you Appetite a psychological desire to consume specific foods the desire is specific to certain foods such a popcorn at the movie theatre or the sight of chocolate cake 3 Roles in Digestion Hypothalamus triggers feelings of hunger or satiation fullness integrates signals from nerve cells in other body regions and from chemical messengers called hormones Sphincters muscles that control the passage of food material from one GIT organ to the next The order of digestion in the GI Tract the mouth esophagus stomach small intestine large intestine anus accessory organs include o pancreas manufactures holds and secretes digestive enzymes o liver synthesizes chemicals for metabolism stores vitamins filters the blood removing wastes and toxins o gallbladder stores bile Food undergoes three processes Digestion large food molecules are broken down into smaller molecules mechanically and chemically Absorption process of taking these products through the intestinal wall Elimination undigested portions of food and waste products are removed from the body Digestion in the Mouth Chewing breaks up food and begins mechanical digestion Epiglottis covers the opening to the trachea during swallowing Taste and Olfactory Receptors detect distinct tastes such as bitter sweet salty etc and detects aromas of food Saliva contains digestive juices secreted by the salivary gland in the mouth Digestion in the Stomach Gastrin a hormone secreted by the stomach lining cells that stimulates the gastric glands to produce gastric juice Gastric Juice Acidic liquid secreted in the stomach Contains hydrochloric acid pepsin and other compounds o hydrochloric acid denatures proteins and activates pepsin o pepsin enzyme to digest protein o gastric lipase enzyme to digest fat o intrinsic factor protein to absorb vitamin B12 Gastric Glands parietal cells secrete HCL and intrinsic factor chief cells secrete pepsinogen and gastric lipase Digestion in the Small Intestine duodeum jejunum and ileum 4 Chyme liquid product of mechanical and chemical digestion in the stomach Mucus layer protects the stomach lining from the acid in gastric juices Bicarbonate neutralizes the acid Ileocecal Valve connects the small intestine to the large intestine Digestion in the Large Intestine Colon Its main function is to store indigested food material and absorb water short chain fatty acids and electrolytes Hydrolysis a chemical reaction that breaks down substances by addition of water Hormones Involved in the Regulation of Digestion Gastrin produced in the stomach Secretin produced in the small intestine Cholecystokinin CCK produced in the small intestine Gastric Inhibitory Peptide produced in the small intestine Four types of Absorption occur in the Small Intestine Passive Diffusion nutrients simply pass through the enterocytes and into the bloodstream without the use of a carrier or energy Facilitated Diffusion requires a carrier protein and does not require energy Active Transport requires energy and a protein carrier to transport nutrients Endocytosis active transport by which a small amount of intestinal contents is engulfed by the cell membrane into the cell Muscles of the Gi Tract Peristalsis waves of squeezing and pushing contractions that move food chyme and feces in one direction through the length of the GI tract Segmentation rhythmic contractions of circular muscles in the intestinal wall Haustration segmentations in the colon that contract sluggishly to move contents located in the colon Mass movement occasionally occurs to move wastes toward the rectum Muscle contractions in the GI Tract Stomach 2 times per minute Small intestine up to 10 times per minutes Haustra 2 times per hour Disorders related to Digestion absorption and excretion Heartburn the painful sensation that occurs over the sternum when hydrochloric acid backs up into the lower esophagus GERD a painful type of heartburn the occurs more than twice per week Peptic ulcer An area of the GI tract that has been eroded away by the acidic gastric juice of the stomach 5 Specific foods immune system Food intolerance gastrointestinal discomfort caused by certain foods that is not a result of an immune system reaction Food allergy An allergic reaction to food caused by a reaction of the Celiac disease a disorder characterized by an immune reaction that damages the lining the small intestine when the individual is exposed to a component of a protein called gluten Inflammatory disorders Crohns disease a bowel disease that causes inflammation in the small intestine leading to diarrhea abdominal pain rectal bleeding weight loss and fever Ulcerative colitis A chronic disease of the large intestine or colon indicated by inflammation and ulceration of the mucosa or innermost lining of the colon Functional Disorders Diarrhea A condition characterized by the frequent passage of loose watery stools Constipation a condition characterized by the absence of bowel movements for a period of time that is significantly longer than normal for the individual Chapter 4 Plant Derived Energy Nutrients What are Carbohydrates Macronutrient Carbon Hydrogen Oxygen Glucose the most abundant carbohydrate Produced by plants through photosynthesis Simple Carbohydrates contain one or two molecules commonly referred to as simple sugars can increase bad cholesterol can decrease good cholesterol Monosaccharides contain one molecule o Glucose fructose galactose Disaccharides contain two molecules o Lactose maltose and sucrose 6 Alpha bond a type of chemical bond that can be digested by enzymes found in the human intestine Beta Bond a type of chemical bond that cannot be easily digested by enzymes found in human intestine Complex Carbohydrates Starch glycogen most fibers Oligosaccharides Contain 3 10 molecules Polysaccharides Consist of hundreds to thousands of glucose molecules Starch Polysaccharide stored in plants Amylose straight chain of glucose Amylopectin branched chain of glucose Glycogen storage form of glucose for animals Not a source of dietary carbohydrate Stored in the liver and muscles Fiber long polysaccharide chains Dietary Fibers non digestible parts of plants Functional Fibers Non digestible forms of carbohydrates extracted from
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